1971 GMC K20 emergency brake.

[k29349]

I have a 1971 GMC K20 that has the hand operated emergency brake. From the research that I have done, I think it's supposed to have the foot operated emergency brake. Also I was looking online for a fuel filler grommet because I cut mine to get the tank out. It looks like my truck had the 70 and earlier grommet. I'm pretty sure this truck is in an original paint truck. The serial number plate does not look like it has been messed with. The truck has disc brakes on the front. Do you guys have any ideas?

[kwmech]

Um, yeah. It's not a 71...well not the cab anyways. Get us a pic of the door jamb where the vin plate is riveted on

[k29349]

Here's a pic.

[57taskforce]

Looks like that plate has been swapped. Those appear to be round rivets not the proper rosette rivets. 69+ cabs have the pedal actuated parking brake. Disk brakes are correct for 71-72 but I don’t believe your cab to be original that would explain your filler neck as well.

[LockDoc]

-
Can you post a picture of the SPID label from the inside the glove box door, and a picture of the dash that shows the ignition switch?

LockDoc

[k29349]

57taskforce, you were right. I went out to get a pic of the spid this morning and noticed the vin #. It's a 68 1/2 ton 6 cly. Would there be a serial number on the frame somewhere? The truck has a 14-bolt rear end in it. It looks like it's been in there forever. It does have the short front springs.

[LockDoc]

-
2 locations for the numbers on the frame. One is on top of the frame near where the steering box bolts on and one is on top of the frame under the center of the cab. (NOT on the side of the frame) Sometimes you can read this one with an inspection mirror.

LockDoc

[k29349]

Thanks Lockdoc!

[special-K]

Chevys are K/20s and GMCs are K2500s. I'm curious what chassis it's on. How are the rear shocks located? pre-73 had both shocks ahead of the rear, so if yours are, the crossmember looks unaltered, as the axle has one shock mount welded on it's pre-73 with a post '72 14-bolt. That's probably what it is since it has the shorter springs on the front.

[k29349]

I will have to go down there and check tomorrow. I do remember that has old crusty faded GMC 2500 Custom badges on the front fenders that look original to the truck. The cab, front fenders, and hood look to be original paint.

[57taskforce]

Man that’s a classy looking truck even if it isn’t original! I feel like the GMC’s really pull the 4x4 look off perfectly.

[k29349]

Thanks! It has a 350 with a sm465 transmission. I thought it was the original engine at first because it says September 1971 on the valve cover. I'm really not too worried about it not being original since I'm never going to sell it. I like the looks of it also even though it has a white bed.

[57taskforce]

I’m thinking going by that vin on the door jam if someone didn’t just drop that 2wd drive body on a 71 gmc frame. That would explain the cab vin plate and the engine.

[k29349]

Here's a pic of the rear frame. Check out that rear lift kit! Is it possible that a 71 GMC would have had a 14-bolt? I wish they would have used a 67 cab while they were cab swapping.

[57taskforce]

Originally Posted by k29349

Here's a pic of the rear frame. Check out that rear lift kit! Is it possible that a 71 GMC would have had a 14-bolt? I wish they would have used a 67 cab while they were cab swapping.

No the 14 didn’t show up until 73. I’ve got one in my K20 as well. I love me a good 14 floater. That looks like a 67-72 frame to me notice the shock mounts Tim mentioned, as well as the rear crossmember placement.

[k29349]

So you think there's a good chance the frame matches the VIN number that they transferred onto the cab? Then maybe just swapped in a 14-bolt later. Also why do many people swap out the handbrake for the foot pedal? Does it actually work better or is it just for a cleaner look?

[57taskforce]

I would check the partial frame vin by the steering box and see if it matches the vin plate. It may buried under dirt and grease but if it’s a 71 it’s probably there but not guaranteed.
It’s been documented on here that the earlier GMCs didn’t always have the vin stamped on the frame so it is possible it may not be there.

[k29349]

I looked on the frame by the steering box but I didn't see anything. Unless it's up under the radiator support.

[57taskforce]

It’ll be roughly in this area, I don’t think I took a picture of mine when I tore it down.
Edit* the bottom picture vaguely shows the stamping on my frame.

[rowdy11]

They are stamped here...and here...both drivers side.

[k29349]

Found this on the side of the frame. And a valve cover pic. Thanks rowdy11

[57taskforce]

Originally Posted by rowdy11

They are stamped here...and here...both drivers side.

My second stamping was on top of the Frame rail Right below the drivers floor pan, not sure if all of them were like that or not honestly.

[57taskforce]

Originally Posted by k29349

Found this on the side of the frame.

I believe that is a part number on the frame not the partial vin.

[k29349]

I took a wire brush to the top of the frame near the steering box. I see nothing.

[57taskforce]

It’s possible unfortunately your GMC frame has no stamping then.